Automatic document handler

ABSTRACT

An automatic document handler for supplying documents singly to the platen of a processing apparatus such as a copying machine. Following copying, each document is returned to the document supply where the used documents are kept separated from documents awaiting copying by means of a resettable bail bar.

United States Patent Hoyer 1 1 June 11, 1974 [541 AUTOMATIC DOCUMENT HANDLER 2,865,055 12/1958 Schumann 74/42 X 3,184,230 5/1965 Rolon 74/86 X [751 August Penfield, NY 3,556,511 1/1971 Howard et a1. 271/4 3 Assigneez xerox corporafion, Stamford, 3,565,420 2/1971 Howard 271/4 Conn. Primary Examiner-Evon C. Blunk [22] led: May 1972 Assistant Examiner-Bruce H. Stoner, Jr. [21] Appl. No.: 250,904

[57] ABSTRACT [52] US. Cl. 271/4, 74/86 An oma i ocum nt handler for supplying docu- [51] Int. Cl B65h 1/26 m nts singly to the platen of a processing apparatus [58] Field of Search 271/4, 3, 5, 18; 74/42, Such as a py g machine Following py ng, each 74/86 document is returned to the document supply where the used documents are kept separated from docu- [56] References Cit d ments awaiting copying by means of a resettable bail UNITED STATES PATENTS 12/1953 Rosswall 271/18 R bar.

2 Claims, 11 Drawing Figures PATENTEDJUN 11 m4 3.815396 SHEET 10! 7 PATENTEDJUMH 1914 381-5886 v sum 30F 7 PATENTEDJunH I974 3.815396 sum 6 OF 7 FIG. 6

AUTOMATIC DOCUMENT HANDLER The principle object of this invention is to provide for the separation of returned documents from those in the stack yet to be copied by a separator bar, and the automatic removal of the separator bar from the bottom of the stack and the positioning thereof on the top of the stack.

This invention relates to a document transport system comprising, in combination, 'means for holding a stack of documents to be transported, processed and returned; means for separating returned documents from those in the stack yet to be processed; a drive linkage for the separating means, comprising a rotary drive crank; a link pivotally connected to the crank, the separating means being connected to the link at a point remote from the crank; a pivot arm having one end pivot ally connected to a fixed point and its other end pivotally connected to the link at a point intermediate the crank connection and the separating means connection, whereby rotation of the drive crank one revolution causes the separating means to traverse a circumambient path out from under a stack of documents in the holding means and then over the stack to the top thereof.

Other objects and advantages will appear from the ensuing description and drawings in which:

FIG. 1 is a side view in cross section showing a document handler incorporating the improved document transport belt of the present invention in operative association with a document copying machine;

FIG. 2 is an isometric view of the document handler shown in FIG. 1;

FIG. 3 is an isometric view showing details of the document separating bail;

FIG. 4 is an isometric view showing the drive details for the main document transports of the document handler shown in FIG. 1;

FIG. 5 is an isometric view showing the drive details for the return document transports of the document handler shown in FIG. 1;

FIG. 6 is a control schematic for the document handler shown in FIG. 1; and

FIG. 7a-e depict a stepwisesequence of the cyclic operation of a separator bar or bail bar and its drive linkage in moving from the bottom of a document stack to the top thereof.

Referring to the drawings, there is shown the document handler, designated generally by the numeral 10 incorporating the platen transport of the present invention. Document handler 10 may be used with any suitable document processing apparatus, such as a copying or reproduction machine 5, which has a platen 6 on which the document to be copied rests.

Document handling apparatus 10 includes a supply tray 12 for storing both documents 7 to be copied and documents 8 already copied. From tray 12, one document at a time is advanced from the bottom of supply 7 by an intermittently operated primary feed roll 14 into the nip of retard roll pair 16, 17. The lower roll 16 is driven in a document feeding direction while the upper roll 17 is driven in the reverse or document reject direction (as shown by the dotted line arrow in FIG. 1) through a suitable slip coupling which normally enables the lower roll 16 to override the reverse drive input to roll 17 and thereby turn roll 17 in the document feeding direction. However, if two or more documents enter the nip of roll pair l6, 17, the reduced friction between the overlapping documents reduces the frictional drive force between roll pair 16, 17, permitting the slip clutch to engage and drive roll 17 in the reverse, document rejecting direction.

The document emerging from retard roll pair 16, 17 passes into the nip of intermediate roll pair 18, 19, and from there underneath deflector plate 21 to platen transport 20. Transport 20, which preferably comprises a belt-type conveyor, first carries the document forward onto platen 6 until the entire document is positioned thereon. Transport 20 is then reversed to bring the document trailing edge against register 22. Register 22 locates the document in copying position following which the copy or copies are made by the copying apparatus 5.

When copying is completed, platen transport 20 is again started in reverse to move the document backwards off platen 6, register edge 22 being previously retracted for this purpose. Deflector 21, which was previously lowered, guides the returning document upwardly into the nip of return roll pair 23. Roll pair 23 move the document along suitable return guides 26 through second and third return roll pairs 27, 28 re spectively, and back into tray 12.

To maintain copied documents which have been designated for convenience by the numeral 18, segregated from documents 7 awaiting copying, and prevent inadvertent or premature refeeding of the returned documents 8 by feed roll 14 folowing feed of the last one of the documents 7, a displaceable bail or separator bar 32 is provided. Bail 32 is disposed substantially opposite to and above primary feed roll 14 to prevent documents resting thereon from contacting roll 14. As will appear, bail 32 may be reset onto the top of the documents in tray 12 when it is desired to refeed the documents to copying machine 5.

Referring now to FIGS. 1 and 2, document tray 12 includes a substantially flat downwardly inclined base 31 and suitable supporting frame 36 carried on copying machine 5 adjacent platen 6. A curved guide 33 leads from base 31 to platen 6, which in the arrangement shown is substantially horizontal. A series of openings 29 in both base 31 and guide 33 accommodate rolls 14, 16 and 18.

As best seen in FIG. 2, a tray assembly 30 is provided A for holding the documents, the tray assembly being comprised of matching right and left hand receptacles 41, 41 respectively. Receptacles 41, 41' are arranged in facing relationship to one another and supported by their lower ends on shaft 42, the receptacle supporting segment of which is rectangular in cross section. Shaft 42 is journaled for rotation in bushings 43 on frame 36 adjacent the bottom of base 31. Shaft 42 carries stop collars 44 at each end between bushings 43 and cover supports 45, the latter serving to support tray cover from shaft 42 as will appear. Cover supports 45 each include a drive lug 45' adapted, following predetermined rotation of the cover 60 in the opening direction to engage a mating shoulder 44' on the adjoining collar 44 and thereby drivingly couple shaft 42 and receptacles '41, 41' thereto.

Receptacles 41, 41 each include a base 46 and outer side 47. The upper portion 47' of receptacle sides 47 are preferably flared outwardly to provide a slightly enlarged entrance facilitating entry of returning documents to the tray assembly 30. The relative narrower sides 47 therebelow aid in aligning the document side edges with one another.

' Receptacles 41, 41' are preferably supported for lateral adjusting movement along the rectangular portion of shaft 42 toward and away from one another to accommodate various size documents. For this purpose, the receptacles 41, 41 are interconnected adjacent their lower end by means of cord 48. Cord 48 is supported around pulleys 49 with one terminal end thereof secured to one tray 41 and the other to tray 41 As can be understood, movement of cord 48 effects simultaneous movement of trays 41, 41 toward or away from one another.

Suitable detent means (not shown) may be provided to maintain the receptacles 41, 41' in pre-selected positions corresponding to conventional document widths. Torsion springs 50 bias receptacles 41, 41' inwardly toward base 31 (in the clockwise direction as seen in FIG. 1), it being understood that contact between base 31 and the bottom 46 of receptacles 41, 41 limits inward movement of receptacles 41, 41'. v

To guide returning documents into the receptacles 41, 41' as well as prevent documents from falling out of the receptacles 41, 41, particularly when bail 32 is reset, a cover 60 is provided. As described, cover 60 is rotatably supported from shaft 42 via supports 45 which enable the cover 60 to be swung open for access to the tray assembly 30 during loading and unloading of documents.

Cover 60 includes an exterior wall 62, which may be suitably decorated, depending sides 63, and interior wall 64, which together form a hollow section or plenum 65. As may be seen in FIG. 2, cover 60 is substantially rectangular in shape, and sized to overlay the entire base 31 including the tray assembly 30. Interior wall 64 of cover 60 is substantially flush with the top edge of receptacle sides 47 when cover 60 is closed, the wall 64 serving as a guide to help route returning documents into receptacles 41, 41' as will appear.

A fan 66 is disposed within the cover plenum 65 opposite outlet 67 in interior wall 64. Fan 66 serves to discharge a low pressure stream of air downwardly through outlet 67 onto the documents therebelow in tray assembly 30. Fan motor 68 is housed in the cover plenum 65 and suitable air inlet openings (not shown) are provided in the cover proper for fan 66.

Cover 60 carries a depending detent and stop member 70 on each side thereof, stop members 70 being slotted at 71 to receive guide pins 72 supported from each side of the frame 36.

Referring particularly to FIG. 3, the bail 32 is carried by arms 81 which are in turn pinned to intermediate links 82. Each link 82 is pivotally supported on the frame 36 through an arm 83. Upstanding frame brackets 36' are provided for this purpose, arm 83 being in effect pinned between brackets 36' and link 82. Intermediate links 82 are also pinned to crank arms 84 carried by the transversely extending output shaft 85 of a one revolution clutch 180. As will appear more fully herein, engagement of clutch 180 turns shaft 85 and crank arms 84 through one revolution.

On rotation of crank arms 84, and due to the interrelationship of links 82 relative to supporting arms 82, 83, bail 32 moves through a generally rectangular path, initially in a forward direction generally parallel to tray base 31, then up away from base 31, then back toward primary feed roll 14, and then down toward base 31.

With reference to any documents in tray 12 which rest on bail 32, bail 32 moves first forward out from under the documents, then raises up to a position above the documents, then moves back to a position above feed roll 14, and then down onto the topmost document. To provide a predetermined bail pressure, springs 86 are provided to bias arms 81 in a downward direction toward tray base 31.

With reference to FIGS. 7a-e, it will be observed that essentially two forces are acting on the intermediate link 82: the first is the circular drive force applied by crank 84 through pivot 401, and the second is the constraint applied by arm 83 pivotally connected to link 82 at 402 and fixedly pivoted at 403 to the machine frame. As crank 84moves in sequence through the positions shown in FIGS. 7a-c, one aspect of the motion tends to pivot the link 82 about point 402 to cause the end 404 of link 82 to traverse an upward arc, with very slight motion of arm 83 as the link 401-402 passes over the rotational center of crank 84. The slight motion of arm 83 that does occur is opposite to the bow in the arc motion of end 404, thereby flattening that are to substantially a straight line. In this action, bail bar 32 follows, and therefore traverses a substantially straight line path as it moves upwardly and out from under the document stack 8. As the crank 84 moves from the position of FIG. 7c to that of FIG. 7d and then to that of FIG. 7e, arm 83 is forced through a substantial arcuate traverse, first to the left as shown in the Figures, and then in retrace to the right. This action causes the end 404 and the bail bar 32 to effect a substantial swing in traversing to the left of document stack 8 and then downwardly and to the right, to overlie the outside of the stack. At this point, the linkage is in the starting position of FIG. 7a, except the bail bar has been moved from under the stack 8 in FIG. 7a to over the stack in FIG. 7e, with the difference in bail bar location being accommodated by the resiliency of spring 86 permitting pivotal movement of arm 81 about its pivotal connection 405 to link 82. Set screw 406 bearing against stop 407 defines the limit of pivotal movement of arm 81 under the influence of spring 86.

A photocell type detector 88 is provided on bail 32. A light 89 for detector 88 is located under base 31 and opposite detector 88, base 31 being suitably apertured for this purpose. As will appear, detector 89 responds in certain circumstances to the absence of documents under bail 32 to actuate clutch 180 and reset the ball 32 as described heretofore.

To obviate buildup of static electricity on the documents, a suitable ion generator 92 is provided adjacent the entrance to the document tray assembly 30. Generator 92, which is connected to a suitable source of electrical energy (not shown), serves to ionize the air through which the documents returning to tray assembly 30 pass to help neutralize any static electric charges that may be on the documents.

Referring now particularly to FIGS. 4 and 5 of the drawings, a suitable drive motor is provided. Motor 100 may be conveniently supported on frame 36 below tray base 31. Motor shaft 101 is connected by means of toothed belt 102 with main power takeoff shaft 103.

The primary feedroll l4, retard roll pair 16, 17, and lower roll 18 of intermediate roll pair 17, 18 are preferably operated at a lower speed than that of platen belt 20 and return roll pairs 23, 27, 28. To provide such low speed drive to rolls 14, 18 and to roll 16 of retard pair 16, 17, a toothed belt 104 drivingly connects shaft 103 with clutch 105 on transfer shaft 106. As will be understood, clutch 105, when actuated, couples power takeoff shaft 103 with transfer shaft 106.

Transfer shaft 106, which is suitably joumaled in frame 36, carries a drive pulley 108 on the outside end thereof. A toothed belt 109 drivingly connects pulley 108 with gear 110 on shaft 111 of the bottom limiting roll 16 and with toothed pulley 112 of overrunning clutch 114. Clutch 1 14 is supported on shaft 115 of the bottom intermediate transport roll 18 and serves to turn shaft 115 in a document feeding direction unless the high speed drive input to shaft 115 is operational,

during which period clutch 114 overruns as will later appear herein.

Primary feed roll 14 is supported by shaft 118 which in turn is suitably joumaled in frame 36. Drive belt 117 drivingly connects shaft 118 with limiting roll support shaft 1 1 1. As will be understood therefore, actuation of clutch 105 drives primary feed roll 14, lower retard roll 16, and lower intermediate transport roll 18 at low speed in a document feeding direction.

Referring now to FIGS. 1, 4 and 5, power takeoff shaft 103 carries a drive pulley 120 on the terminal end thereof. Pulley 120 is connected with pulley 121 on stub shaft 122. Gear 123 on pulley 121 meshes with gear 124 on shaft 125 supporting the lower rolls of return transport roll pair 28. A toothed belt 126 drivingly connects shaft 125 with shaft 127 supporting the lower rolls of return transport pair 27. A second belt 128 drivingly interconnects shaft 125 with shaft 130 supporting the lower rolls of return transport pair 23. The upper rolls of the return transport roll pairs 23, 27, 28 are supported upon idler shafts 132 suitably joumaled in return transport sub-frame 36.

Referring particularly to FIG. 4, shaft 125 carries a gear 133 on the end thereof which, in turn, drives, through intermediate gearset 134, gear 135 of a hysteresis type clutch 136. Shaft 137 of clutch 136 is suitably joumaled in transport subframe 36". Gear set 138 drivingly couples clutch shaft 137 with the retard roll 17. As will be understood, therefore, engagement of clutch 136 drivingly couples clutch shaft 137 with driven shaft 125 to turn retard roll 17 via gearset 138 in the reverse or document rejecting direction (shown by dotted arrow in FIG. 6).

Hysteresis clutch 136 is preset to engage whenever the reverse torque applied to shaft 137 generated through contact of roll 16 with retard roll 17, either directly or through the intermediary of one or more documents therebetween, falls below a predetermined level. This normally occurs whenever more than one document at a time attempts to pass between the retard roll pair l6, 17. At other times, clutch 136 is effectively disengaged and retard roll 17 turns with roll 16 in the document feeding direction.

To provide the reversible relatively high speed drive to platen transport 20, a double clutch 140 is provided on an intermediate transfer shaft 142. As will be seen in FIG. 4, one side of clutch 140 carries a forward drive gear coupled to power take off shaft 103 by means of gear 148. The other side of clutch 140 carries reverse drive pulley 143 coupled to shaft 103 via toothed belt 144.

Output pulley on shaft 142 is drivingly coupled by toothed belt 151 with idler gear 152 on stub shaft 153. A second pulley 154 on shaft 153 is coupled by toothed belt 155 with pulley 156 on shaft 157 of platen transport roll 231. Gear 158 on stub shaft 153 meshes with gear 159 of one-way clutch 160 on shaft 115 of lower intermediate transport roll 18. One-way clutch 160 functions to drivingly connect shaft 115 and lower intermediate transport rolls 16 with transfer shaft 142 whenever clutch 140 is engaged in the forward document feeding direction to provide high speed drive to roll pair 18, 19. On engagement of clutch 140 in the reverse feeding direction, clutch 160 disengages to prevent reverse rotation of intermediate transport roll pair 18, 19. The upper intermediate transfer roll 19 is supported on idler shaft 161 suitably joumaled in frame 36.

The drive ratios between shaft 103 and the pulley and gear input to clutch 140 are chosen to operate platen transport 20 at a relatively higher speed than that of primary feed roll 14. Since the lower intermediate feed roll 18 is subject to both high and low speed drive input, overrunning clutch 114 additionally serves to accommodate overruning of roll 18 when both clutches 105 and 140 are simultaneously engaged.

In summary, high speed drive from motor 100 is conducted by clutch 140 in either the forward or reverse direction to platen transport 20. Where clutch 140 is engaged in the forward direction, intermediate feed roll pair 18, 19 are turned at high speed.

Bail clutch has an input gear 183 drivingly connected by belt 184 with stub shaft 186. Gear 187 on shaft 186 is driven from reverse drive gear 145 through suitable intermediate gears (not shown) designed to drive belt 184 at the proper speed and in the proper direction. Clutch 180 comprises a suitable solenoid actuated one revolution clutch effective when engaged to turn crank arms 84 through one revolution and thereby reset bail 32.

In FIG. 6 of the drawings, a control arrangement for the document handler 10 is there schematically shown. In that arrangement, a suitable controller 301 is provided to integrate operation of the various components of the document handler with each other and with the apparatus with which document handler 10 is used such as copying apparatus 5. To provide the requisite timing intervals controller 301 includes a suitable timing or counting device (not shown) driven by means of clock disc 302 on power transfer shaft 103, there being a suitable signal generator here shown as photocell 304, and light source 305 disposed on opposite sides of disc 302. Note FIG. 4. Apertures 303 in disc 302 permit light from light source 305 to intermittently strike photocell 304 as disc 302 rotates to provide a clocklike input pulse.

Starting and stopping of document handler motor 100 may be conveniently effected by means of a suitable manually operated start-stop control 308. In the arrangement shown, operation of the document handler 10 is dependent upon enabling signals from copying machine 5, tray cover safety switch 80 and platen transport safety switch 309, respectively. Switches 80, 309 reflect disposition of tray cover 60 and platen transport 20 in their closed operating positions. It is understood that other contingency controls may be provided.

In operation, and referring particularly to FIGS. 1, 4 and 6, the documents 7 to be copied are placed in tray assembly 30 trailing edge down, the document or docu- 7 ments resting atop bail 32. It is understood that receptacles 41, 41 are adjusted for proper document size.

With stop-start control 308 actuated and platen transport 20 lowered, closing cover 60 starts document handler motor 100. It is understood that return transport roll pairs 23, 27, 28, whichare directly coupled to motor 100, are driven whenever motor 100 is energized.

At start-up, detector 88 on bail 32 signals the absence of documents therebelow. In response thereto, controller 301 engages bail clutch 180 to move bail 32 through one cycle from a position below the documents in tray 12 to a position on top of the documents in the manner explained heretofore.

With bail 32 properly positioned atop the documents 7 in tray assembly 30, controller 301, in response to the document demand signal of wait station detector 312 at the entrance to platen 6, actuates clutch 105 to drivingly couple primary feed roll 14, retard roll pair 16, 17 and intermediate feed roll pair 18, 19 with motor 100. Rotation of feed roll 14 advances the bottommost document in tray 12forward through retard roll pair l6, 17

which guard against feeding of double sheets, and into the nip of intermediate roll pair 18, 19 operating at low speed.

As the leading edge of the first document moves out of roll pair 18, 19 and comes opposite detector 312, controller 301 actuates clutch 140 to couple gear 145 to drive shaft 142 and thereby operate intermediate feed roll pair 18, 19 and platen transport 20 in the forward direction to advance the waiting document onto platen 6. It is understood that engagement of clutch 140 in the document forward feed direction drives intermediate feed roll pair 18, 19 at high speed, overrunning clutch 114 accommodating the difference in driving input speed in the event primary feed clutch 140 is engaged.

Following a predetermined interval sufficient to allow the trailing edge of the document to pass over and slightly beyond the register 22, controller 301 switches clutch 140 from forward to reverse drive, the latter coupling drive pulley 143 with shaft 142.

Platen transport 20 is therefore reversed and the document moved backwards on platen 6 until the rear or trailing edge thereof abuts against register 22. Abutment of the document edge with the edge of register 22 locates the document in predetermined copying position. With document movement prevented by register 22, belt 20 slides across the document surface until clutch 140 is disengaged. It is understood that one-way clutch 160 prevents reversing of intermediate feed roll pair 18, 19 upon reversing of platen transport 20.

Platen transport 20 is operated in reverse by controller 301 for an interval sufficient to allow transport 20 to bring the document trailing edge against register 22, at which point clutch 140 is disengaged and platen transport 20 stopped. With the document in copying position, copying apparatus is then enabled to begin the copying cycle.

As the trailing edge of the first document moves past wait station detector 312, controller 301 again engages clutch 105 in response to the demand signal from detector 312. Rolls 14; 16, 17; and 18, 19 are therefore operated to bring the next or second document forward as explained heretofore. When the leading edge of that document reaches detector 312, controller 301 disengages clutch 105 to prevent feeding of another document. At this point therefore, the first document is in copying position on platen 6 while the second document is in a waiting position adjoining the inlet to platen 6.

On completion of the copying cycle, controller 301 actuates register drive clutch 170 to retract register 22 and lower deflector 21. When retraction of register 22 and lowering of deflector 21 has been completed, controller 30 actuates clutch in the reverse drive mode to couple belt 144 with shaft 142. Platen transport 20 is therefore driven in reverse to move the document off platen 6. As the document moves off of the platen, deflector 21 routes the document into the nip of first return transport roll pair 23. Roll pair 23 cooperate with return guides 26 and roll pairs 27, 28 to carry the document back to tray 12 where the document is deposited into receptacles 41, 41 atop bail 32.

As the trailing edge of the returning document passes a return document detector 315, controller 301 actuates register drive clutch to bring register 22 forward 'to registering position on platen 6. At the same time, deflector 21 is raised. With register 22 in position, controller 301actuates clutch 140 in the forward drive mode to couple gear 145 with shaft 142 and operate intermediate feed roll pair 18, 19 and platen transport 20 in the document feeding direction at high speed. Actuation of feed roll pair 18, 19 and transport 20 moves the waiting document onto platen 6 and into registered position as described heretofore. And, with advance of the next document forward from the waiting station, controller 301, in response to the demand signal from detector 312, engages clutch 105 to bring the next document forward from tray assembly 30 into waiting position as described.

The aforedescribed cycle of operation continues until the last document is fed from under bail 32. On that event, controller 301, in response to a signal from the document detector 88 on bail 32, engages clutch to reset bail 32 as described.

At this point, the last of the documents originally placed in tray assembly 30 is normally at the waiting station defined by detector 312. If bail 32 is to be restored to its original position atop the last document of the document supply, the bail must be reset again after the last document is returned to the tray assembly 30. To effectuate this, controller 301, on a last document signal from copying machine 5 and following the elapse of a predetermined time interval adequate to allow the last document to reach tray assembly 30, again actuates bail clutch 180 to reset bail 32.

In cases where a single document cycle is desired, resetting of bail 32 may be omitted to facilitate removal of the documents from tray 12. Similarly, resetting of bail 32 may be omitted on the last cycle of a multiple copy cycle for this purpose.

While the invention has been described with reference to the structure disclosed, it is not confined to the details set forth, but is intended to cover such modifications or changes as may come within the scope of the following claims.

What is claimed is:

1. In a document transport system having means for holding a stack of documents to be transported, processed and returned. and means for separating returned documents from those in the stack yet to be processed; the improvement of a drive linkage for said separating means comprising a rotary drive crank, a link pivotally connected to said crank, said separating means being connected to said link at a point remote from said crank, a pivot arm having one end pivotally connected to a fixed point and its other end pivotally connected to said link at a point intennediate said crank connection and said separating means connection, said intermediate point being offset from a line between said pivotal connection of said link crank and said point remote from said crank pivotal means connecting said separating means to said link at said point remote from documents from those in the stack yet to be processed; the improvement of a drive linkage for said separating means, comprising a rotary drive crank, a link pivotally connected to said crank, said separating means being connected to said link at a point remote from said crank, a pivot arm having one end pivotally connected to a fixed point and its other end pivotally connected to said link at a point intermediate said crank connection and said separating means connection, pivotal means connecting said separating means to said link at said point remote from said crank, and means biasing the last-mentioned pivotal means in one pivotal direction whereby rotation of said drive crank one revolution causes said separating means to traverse a circumambient path out from under a stack of documents in said holding means and then over said stack to the top thereof. 

1. In a document transport system having means for holding a stack of documents to be transported, processed and returned, and means for separating returned documents from those in the stack yet to be processed; the improvement of a drive linkage for said separating means comprising a rotary drive crank, a link pivotally connected to said crank, said separating means being connected to said link at a point remote from said crank, a pivot arm having one end pivotally connected to a fixed point and its other end pivotally connected to said link at a point intermediate said crank connection and said separating means connection, said intermediate point being offset from a line between said pivotal connection of said link crank and said point remote from said crank pivotal means connecting said separating means to said link at said point remote from said crank, and means biasing the last-mentioned pivotal means in one pivotal direction whereby rotation of said drive crank one revolution causes said separating means to traverse a circumambient path out from under a stack of documents in said holding means and then over said stack to the top thereof.
 2. In a document transport system having means for holding a stack of documents to be tranported, processed and returned, and means for separating returned documents from those in the stack yet to be processed; the improvement of a drive linkage for said separating means, comprising a rotary drive crank, a link pivotally connected to said crank, said separating means being connected to said link at a point remote from said crank, a pivot arm having one end pivotally connected to a fixed point and its other end pivotally connected to said link at a point intermediate said crank connection and said separating means connection, pivotal means connecting said separating means to said link at said point remote from said crank, and means biasing the last-mentioned pivotal means in one pivotal direction whereby rotation of said drive crank one revolution causes said separating means to traverse a circumambient path out from under a stack of documents in said holding means and then over said stack to the top thereof. 